A liquid crystal display apparatus is a flat panel display apparatus having excellent features such as high definition, reduction of thickness and weight, low power consumption and the like. The liquid crystal display apparatus is widely used for a thin type television, a personal computer monitor, a digital signage and the like.
Conventionally, a TN (twisted nematic) mode liquid crystal display apparatus, which has been generally used in the art, allows for excellent manufacturing productivity. On the other hand, the TN mode liquid crystal display apparatus has problems in viewing angle characteristics related to screen display. For example, when viewing the display screen from an oblique direction with respect to a normal line, a contrast ratio is remarkably decreased in the TN mode liquid crystal display apparatus, and a luminance difference between gradations becomes remarkably unclear. In addition, a so-called gradation inversion phenomenon is often observed. In gradation inversion phenomenon, there are portions that appear bright (or dark) when viewing the display screen from a front and appear dark (or bright) when viewing it from the oblique direction with respect to the normal line.
As a liquid crystal display apparatus for improving the above-described problems of the viewing angle characteristics, there is a liquid crystal display apparatus for performing display in a display mode such as an IPS (in-plan switching) mode, an MVA (multi domain vertical alignment) mode or the like. As a technique for improving the viewing angle characteristics, techniques that realize the display mode of these liquid crystal display apparatuses are widely used.
One problem of the viewing angle characteristics is that the gamma characteristic, representing gradation dependency of the display luminance, depends on an angle of a visual line with respect to the normal line of the display screen (hereinafter referred to as visual angle dependency of the gamma characteristics). This problem is that a gradation display state varies depending on an observation direction with respect to the display screen, and that the gamma characteristic is differently observed between a case where the observation direction is along the normal line of the display screen and a case where the observation direction is the oblique direction with respect to the normal line.
‘82” Ultra Definition LCD Using New Driving Scheme and Advanced Super PVA Technology’ by Sang Soo Kim, Bong Hyun You, Jung Hwan Cho, Sung Jae Moon, Brian H. Berkeley and Nam Deog Kim, SID Symposium Digest of Technical Papers, May 2008, Volume 39, Issue 1, p. 196-199 discloses a liquid crystal display apparatus that improves the visual angle dependency of gamma characteristics (referred to as viewing angle dependency in some documents). In the liquid crystal display apparatus described in ‘82” Ultra Definition LCD Using New Driving Scheme and Advanced Super PVA Technology’ by Sang Soo Kim, Bong Hyun You, Jung Hwan Cho, Sung Jae Moon, Brian H. Berkeley and Nam Deog Kim, SID Symposium Digest of Technical Papers, May 2008, Volume 39, Issue 1, p. 196-199, each pixel includes two sub-pixels, and a discharge capacitor (Cdown) is provided in one sub-pixel. Sub-pixel electrodes of each of the two sub-pixels are connected to a data signal line (source signal line) through a TFT 1 and a TFT 2. A scanning signal is applied to control electrodes of the TFT 1 and TFT 2 from a scanning signal line. Regarding the discharge capacitor, a discharge capacitor electrode opposed to a counter electrode is connected to the sub-pixel electrode of one sub-pixel through a TFT 3. Then, a control electrode of the TFT 3 is connected to a scanning signal line of the next line.
In the liquid crystal display apparatus described in ‘82” Ultra Definition LCD Using New Driving Scheme and Advanced Super PVA Technology’ by Sang Soo Kim, Bong Hyun You, Jung Hwan Cho, Sung Jae Moon, Brian H. Berkeley and Nam Deog Kim, SID Symposium Digest of Technical Papers, May 2008, Volume 39, Issue 1, p. 196-199, regarding each pixel, a scanning signal delayed by one horizontal scanning time from the scanning signal for the pixel is applied to the control electrode of the TFT 3. As such, the sub-pixel electrode and the discharge capacitor electrode of one sub-pixel are connected with each other depending on a signal delayed in time from the scanning signal. Thereby, an effective voltage applied to a liquid crystal layer by each of the two sub-pixels can be changed. In this case, each pixel is observed in a state in which different gamma characteristics for each sub-pixel are harmonized with each other so that the visual angle dependency of the gamma characteristics is improved.